what is the diffrence inode bitmap and inode table

abhishek picture abhishek · Mar 22, 2014 · Viewed 8.6k times · Source

I am trying to understand the difference between inode bitmap and inode table (from ext2 file system documentation), but I am not getting it. Can any one explain?

Answer

Paulo Bu picture Paulo Bu · Mar 22, 2014

The bitmap just occupies one block and is a sequence of 0s and 1s where 0 means that the corresponding inode in the _inode_table_ is free and 1 specified that it's used.

The inode table is where the actual information about the inode is written and it occupies more than one block on the filesystem.

The bitmap technique is useful to quickly find free locations on the inode table (or data blocks) when modifying the filesystem.

On the hard drive, those sections would look like this:

 inode bitmap:
 11100011010010101...

 inode table:
 struct inode | struct inode | struct inode | struct inode | ...